Electric-furnace carbon electrode.



A. T. HINCKLEY. ELBCTP. GGGGGGGGGGGGGGGGGGGGGGG E.

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1,058,057, Patented Apr. 8, 1913.

UNITED STATES PATENT OFFICE.

ARTHUR T. HINCKLEY, 0F NIAGARA FALLS, NEW YORK, ASSIGNOR T0 NATIONAL'CABBON COIPANY, OF CLEVELAND, OHIO, A CORPORATION OF NEW JERSEY.

ELECTRIC-FURNACE CARBON ELECTBDDE.

Specification of Letters Patent.

Patented Apr. 8,1913.

Application filed February 2, 1912. Serial No. 674,986.

new and useful Improvement in Electric- Furnace Carbon Electrodes, ofwhich the following is a full, clear, and exact description.

The object of this invention is to increase the durability of carbonelectrodes, especially of the larger sizes, when used in elec-' tricfurnaces; and particularly .to reduce the chances that such carbonelectrodes will break or shale as the result of differences intemperature of the outer-and inner parts of said electrodes, whichresult from .put-

ting them into or taking them from electric furnaces.

When a large carbon electrode of the ordinary construction is put intoan electric furnace at high temperature, the electrode will becomeintensely hot on the outside, while the center thereof is stillcomparatively cool. This is owing to the fact that the heat conductivityof carbon is relatively low. It may well happen that a carbon electrode,of say 14 inches diameter, may be so heated that its center will be at atemperature of 500 only, while the outer surface may have a temperatureof say 1000 The disruptive force caused by these temperature differencesis very great, and much breakage of electrodes results therefrom, aswill be readil understood if one considers that the coeflicient oftensile elasticity of such carbon is only about one-tenth that ofconstruction that the above mentioned undesirable action occurs rarerlwhen the electrodes put into or us When the electrodes do not inelectric furnace work. Said electrode is tubular and has a narrowlongitudinal slit extending from the outer surface to the central hole,and extending from end to end.

In thedrawing, Figure 1 is a perspective view of a carbonelectrodeembodying this invention; and Fig. 2 is an end view thereof.

- Referring to the parts by letters, A represents a tubularelectrode;that is to say, an electrode having a longitudinal hole a runningthrough it from end to end. Ad-

ditionally, a narrow slit a is formed from the hole to the outersurface, which slit is extended from end to end of said electrode. Suchelectrodes may be made of any suitable carbon or carbonaceous mix,'andmay be compressed and'iformed in any manner before bakin and may haveany desired external con guration.

'It is evident that, in an electrode A having a hole a running, throughit lengthwise in the center, the distance through which the disruptiveforce of temperature differences will act is reduced from the radius ofthe electrode to one-half the thickness of the annular wall; because, byconvection, the exposed surface of the wall of the hole reaches furnacetemperature substantially as soon as the external surface. There will,of course, be some unequal expansion which might cause breakage evenwith a tubular carbon, but the liability that this unequal ex pansionshall produce the injurious results referred to is practicallyeliminated by' the longitudinal slit referred to. If this slit in a 16inch carbon isone-quarter of an inch wide it will serve its purposeadmirably.

Having described my invention, I claim A carbon electrode for electricfurnace work having a hole formed through it' longitudinally from end toend, and having through its wall a narrow slit which also extendsfromend to end.

In testimony whereof, I hereunto aflix my signature inthe presence oftwo witnesses.

